Because we received an error in the log on: BACKUP_PRIVILEGE and RESTORE_PRIVILEGE, this means that we don’t have permissions on Back up files and directories and Restore files and directories.

If you double clicked the definition and you can’t add your user (it’s grayed out) this means that it comes from the domain . In my case these two definitions came from the domain controller’s group policy. I have changed this definitions back to “Not Defined” on the domain controller. Otherwise add the user manually.